| CARVIEW |
Select Language
HTTP/2 200
content-type: text/html
x-guploader-uploadid: AAwnv3Ja1YJROPVAPDUlR-oyt8yyFbioMmxBzHxn5Xe2TCJQFnHmzkl17JSftgekiD7Z-zNh
cache-control: public, max-age=3600
expires: Sat, 11 Oct 2025 12:31:52 GMT
last-modified: Fri, 10 Oct 2025 01:12:15 GMT
etag: W/"7001fa6830948cdc22fa2322519e881b"
x-goog-generation: 1760058735512844
x-goog-metageneration: 1
x-goog-stored-content-encoding: identity
x-goog-stored-content-length: 162055
x-goog-meta-goog-reserved-file-mtime: 1760057110
x-goog-hash: crc32c=9Y55Qg==, md5=cAH6aDCUjNwi+iMiUZ6IGw==
x-goog-storage-class: STANDARD
accept-ranges: none
alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
alt-svc: clear
referrer-policy: strict-origin-when-cross-origin
x-content-type-options: nosniff
strict-transport-security: max-age=63072000
content-security-policy: default-src 'self'; script-src 'report-sample' 'self' 'wasm-unsafe-eval' https://www.google-analytics.com/analytics.js https://www.googletagmanager.com/gtag/js assets.codepen.io production-assets.codepen.io https://js.stripe.com 'sha256-XNBp89FG76amD8BqrJzyflxOF9PaWPqPqvJfKZPCv7M=' 'sha256-YCNoU9DNiinACbd8n6UPyB/8vj0kXvhkOni9/06SuYw=' 'sha256-PZjP7OR6mBEtnvXIZfCZ5PuOlxoDF1LDZL8aj8c42rw='; script-src-elem 'report-sample' 'self' 'wasm-unsafe-eval' https://www.google-analytics.com/analytics.js https://www.googletagmanager.com/gtag/js assets.codepen.io production-assets.codepen.io https://js.stripe.com 'sha256-XNBp89FG76amD8BqrJzyflxOF9PaWPqPqvJfKZPCv7M=' 'sha256-YCNoU9DNiinACbd8n6UPyB/8vj0kXvhkOni9/06SuYw=' 'sha256-PZjP7OR6mBEtnvXIZfCZ5PuOlxoDF1LDZL8aj8c42rw='; style-src 'report-sample' 'self' 'unsafe-inline'; object-src 'none'; base-uri 'self'; connect-src 'self' developer.allizom.org bcd.developer.allizom.org bcd.developer.mozilla.org updates.developer.allizom.org updates.developer.mozilla.org https://*.google-analytics.com https://*.analytics.google.com https://*.googletagmanager.com https://incoming.telemetry.mozilla.org https://observatory-api.mdn.allizom.net https://observatory-api.mdn.mozilla.net https://api.github.com/search/issues stats.g.doubleclick.net https://api.stripe.com; font-src 'self'; frame-src 'self' interactive-examples.mdn.mozilla.net interactive-examples.mdn.allizom.net mdn.github.io live-samples.mdn.mozilla.net live-samples.mdn.allizom.net *.mdnplay.dev *.mdnyalp.dev *.play.test.mdn.allizom.net https://v2.scrimba.com https://scrimba.com jsfiddle.net www.youtube-nocookie.com codepen.io survey.alchemer.com https://js.stripe.com; img-src 'self' data: *.githubusercontent.com *.googleusercontent.com *.gravatar.com mozillausercontent.com firefoxusercontent.com profile.stage.mozaws.net profile.accounts.firefox.com developer.mozilla.org mdn.dev interactive-examples.mdn.mozilla.net interactive-examples.mdn.allizom.net wikipedia.org upload.wikimedia.org https://mdn.github.io/shared-assets/ https://mdn.dev/ https://*.google-analytics.com https://*.googletagmanager.com www.gstatic.com; manifest-src 'self'; media-src 'self' archive.org videos.cdn.mozilla.net https://mdn.github.io/shared-assets/; child-src 'self'; worker-src 'self';
x-frame-options: DENY
origin-trial: AxVILwizhbMjxFeHOn1P3R8niO1RJY/smaK4B4d1rLzc1gTaxtXMSaTi+FoigYgCw40uFRDwFcEAeqDR+vVLOW4AAABfeyJvcmlnaW4iOiJodHRwczovL2RldmVsb3Blci5tb3ppbGxhLm9yZyIsImZlYXR1cmUiOiJQcml2YXRlQXR0cmlidXRpb25WMiIsImV4cGlyeSI6MTc0MjA3OTYwMH0=
x-cloud-trace-context: e1bcff5851a18f2f433ad361b22e9591
date: Sat, 11 Oct 2025 11:31:52 GMT
server: Google Frontend
via: 1.1 google
vary: Accept-Encoding
content-encoding: gzip
x-cache: miss
WeakMap.prototype.get() - JavaScript | MDN
Toggle sidebar
このページはコミュニティーの尽力で英語から翻訳されました。MDN Web Docs コミュニティーについてもっと知り、仲間になるにはこちらから。
WeakMap.prototype.get()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since 2015年7月.
get() メソッドは、WeakMap オブジェクトから指定された要素を返します。
試してみましょう
const weakmap1 = new WeakMap();
const object1 = {};
const object2 = {};
weakmap1.set(object1, 42);
console.log(weakmap1.get(object1));
// Expected output: 42
console.log(weakmap1.get(object2));
// Expected output: undefined
構文
wm.get(key);
引数
key-
必須。
WeakMapオブジェクトから返す要素のキーです。
返値
指定されたキーと関連した要素を返します。キーが WeakMap オブジェクトに見つからない場合、 undefined を返します。
例
get() メソッドの使用
js
var wm = new WeakMap();
wm.set(window, "foo");
wm.get(window); // "foo" を返す
wm.get("baz"); // undefined を返す
仕様書
| Specification |
|---|
| ECMAScript® 2026 Language Specification # sec-weakmap.prototype.get |
ブラウザーの互換性
Loading…